Revert "[rbrowser] Make fCleanupHandle a pointer to TObject"

[vepadulano]

I'd like to start testing again the case highlighted by #13361

Note at the beginning: the issue arose with runtime_cxxmodules=OFF and I'm not sure we have that in the CI so we might not see errors right away

[github-actions]

Test Results

    18 files      18 suites   4d 6h 39m 2s ⏱️
 2 683 tests  2 681 ✅ 0 💤 2 ❌
46 598 runs  46 596 ✅ 0 💤 2 ❌

For more details on these failures, see this check.

Results for commit 4a1a56c.

♻️ This comment has been updated with latest results.

[linev]

One should test with runtime_cxxmodules=OFF

[vepadulano]

One should test with runtime_cxxmodules=OFF

Indeed, it's what I wrote in the PR description. I hoped that we had at least one build with that option. This means that currently there is no build with runtime_cxxmodules=OFF and we should understand if that's intended/desirable or not.

[linev]

I tried runtime_cxxmodules=OFF on my desktop Linux and it works well.

[linev]

Looks fine

[vepadulano]

@linev No it's not unfortunately. As you can see from the runtime_cxxmodules=OFF build of the CI, we still have the same errors on ROOT master:

  Error in <TProtoClass::FindDataMember>: data member with index 0 is not found in class tuple<ROOT::RBrowserDataCleanup*,default_delete<ROOT::RBrowserDataCleanup> >
  Error in <CreateRealData>: Cannot find data member # 0 of class tuple<ROOT::RBrowserDataCleanup*,default_delete<ROOT::RBrowserDataCleanup> > for parent ROOT::RFileDialog!
  Error in <TProtoClass::FindDataMember>: data member with index 1 is not found in class tuple<ROOT::RBrowserDataCleanup*,default_delete<ROOT::RBrowserDataCleanup> >
  Error in <CreateRealData>: Cannot find data member # 1 of class tuple<ROOT::RBrowserDataCleanup*,default_delete<ROOT::RBrowserDataCleanup> > for parent ROOT::RFileDialog!
  Second verify all classes for any overlaps

So this PR #13900 was not enough to fix the issue. In fact, judging from the discussion at #15733, we would need at least to wait until #16202 is merged. Maybe then both the issue in this PR and in #15733 will be fixed.